Capsules are dosage form in which a composition comprising a drug is enclosed within a wall. Capsules are a popular method for administering a drug in both prescription practice and in over-the-counter practice. Capsules are used widely in hospitals, nursing homes, retirement centers, homes, and in other environments, such as the military and naval environments. Capsules enjoy this popularity because they are tasteless, essentially innocuous, easily administered, easily filled extemporaneously, and they can be manufactured in large numbers. Additionally, some capsule users find it easier to swallow capsules than other dosage forms, such as a solid tablet.
While the above advantages and patient preference contribute to the continuing acceptance of capsules, there are certain shortcomings associated with capsules. For example, after oral administration, capsules give up all their useful drug immediately. That is, capsules are dose-dumping dosage forms. The therapeutic consequence of this dose-dumping is non-controlled therapy consisting of an initially high dose of drug, followed by a total absence of drug between later administered capsules. For many drugs, this form of administration can have undesirable therapeutic effects, especially if the drug has a low therapeutic index and is not suited to time-varying rates of administration. Another shortcoming associated with capsules is they are poorly suited for administering drugs with short biological half-lives, and this results in exclusion of large drugs including mammalian biochemicals, natural hormones, humoral factors, and the like.
Yet another shortcoming associated with capsules is their instant delivery and its accompanying detrimental effects. Because of this inherency, capsules require a high frequency of use, and this can lead to a failure of patient compliance for a prescribed dosage schedule. Such failures are reflected in a lack of therapeutic effectiveness, and in possible toxic effects. The latter effects can occur when patients double or triple their dosage to compensate for their prior omissions. Faulty non-compliance associated with the use of capsules is a common and largely ignored problem.
It will be appreciated by those versed in the drug delivery art in the light of this presentation that if a dosage form is provided comprising a capsule that is essentially free of the tribulations known to the prior art, such a dosage form comprising a capsule would have a positive therapeutic value and it would also represent an unexpected advancement in the drug delivery art. The present invention advances the state of the drug delivery art by providing a dosage form manufactured to house a capsule for optimizing the therapeutic effects of a drug. The dosage form comprising the capsule administers a drug at a controlled rate for a prescribed period of time. The dosage form provides continuous control over the administration of the drug, and it maintains this control over an extended period of time.